BitsUndBolts wrote on 2023-01-07, 15:14:

I have used the latest BIOS mod with unlocked voltages on an ASUS P3B-F and published the follow-up video Undervolted Pentium II - Tying up loose ends.
In this video, I could undervolt a PII and PIII to 1.45/1.50 Volts and I did not encounter any issues.

Thanks for the follow-up! That's a substantial drop in voltage. Reminds me a bit of the cD0 Coppermine-T cores, which have good chances of operating at 1.35 V or even 1.30 V instead of the advertised 1.75 V.

RaVeNsClaw wrote on 2023-01-07, 17:01:

I will try the build, but sadly it will take a few days.

Today I recapped multiple mainboards, the CUBX among them.
Only in the middle of the second ASUS board I noticed, that the polarity markings on ASUS mainboards are all reversed.

Quite a bummer. Good luck with the second round of recapping!

maxtherabbit wrote on 2023-01-07, 23:39:

2x115MHz FSB‼‼ Working like a charm‼‼
20230107_183814.jpg
20230107_183639.jpg

Excellent; great to see. 😁 Which OS now, Windows NT or OS/2? 😉

DenizOezmen wrote on 2022-12-28, 10:49:

No worries ... :-) I haven't explained most of the changes in detail yet. […]
Show full quote

B24Fox wrote on 2022-12-28, 04:19:

I hope my question doesn't come off as dumb, or something like that (especially since it's kinda late night, and also I haven't read through the whole thread)

No worries ... 😀 I haven't explained most of the changes in detail yet.

B24Fox wrote on 2022-12-28, 04:19:

Anyway..
regarding this fix: "fixed Hardware Monitor errors and erroneous readings ("-6.14V") when using modern PSUs without a -5 V rail"

have you (ore anyone) probed with a multimeter on the Mobo ATX connector where the white wire (-5V rail) should have been, in order to check if maybe... by some chance.. the mobo circuitry does some weird stuff, and there IS actually -6V there (even though maybe at a very low Amperage) ..??

I assume that not to be the case, but personally haven't ruled it out.

This is what happens on the monitoring side: The onboard hardware monitoring chip outputs voltage readings as a single byte with a resolution of 16 mV. Ordinarily, this means a range of 0 mV to 255 * 16 = 4080 mV can be monitored on each input. Since this is obviously not suitable for the +/-5 V and +/-12 V rails, resistors are added to the appropriate inputs of the monitoring chip to reduce the voltages to the acceptable input range. The BIOS knows the values of these resistors and converts the single-byte reading accordingly:

v5neg = -r * 16 * 909 / 604

The weird values depend on the resistors. It seems like ASUS has followed the recommendations of the manufacturer as documented in the datasheet.

With this shift in place, the new range is now 0 mV to approx. -6140 mV (= -255 * 16 * 909 / 604). And this is where the "-6.14V" display comes from: It basically means that the monitoring chip outputs a value at the edge of its range. This also implies: If the PSU attached to the board actually did have a -5 V rail that had gone completely out of spec (let's say to -10 V), the BIOS would never show a more extreme value than -6.14 V.

So, in theory, there might actually be a weird voltage in place of the -5 V rail, but it doesn't necessarily have to be around -6 V.

On the other hand, the monitoring chip also seems to output maximum readings if there's nothing at all connected to the corresponding input: Regarding the fans, the ASUS stock BIOS interprets a speed reading of 255 as "no fan connected" and displays "N/A", even though this value could also be interpreted as a speed of around 1300 RPM. I simply applied the same logic to the -5 V rail display.

In any case, the -5 V rail patch does not change the voltage on that rail, so whatever the situation, it doesn't get worse due to the mod. The only drawback: Since the monitoring circuit cannot differentiate between a missing voltage and a voltage that is way out of spec, and the mod now decides on "no voltage present", you won't get a hardware monitor error anymore for an old PSU with a -5 V rail that has suddenly strayed to -6.14 V or beyond. That might be something to keep in mind.

B24Fox wrote on 2022-12-28, 04:19:

Also, does this fix: "support of additional voltage ranges to suppress Hardware Monitor errors at bootup" ACTUALLY adds more voltage options that the hardware could actually provide? or is it just a variable added to make the Hardware Monitor shut up?

It's the latter. The hardware monitor code checks the actual VCore reading against a hard-coded list of voltage ranges depending on the processor type. If the reading does not fall into the expected range for the processor that has been detected, the logic signals an error. The mod only extends this list with new ranges appropriate for Tualatin cores, Pentium Pros and the various Via C3 cores.

(Side note: Newer builds like that on the P3C-E seem to work differently here and determine the appropriate range dynamically, possibly in reference to the voltage requested by the CPU itself. I haven't looked into that thoroughly, though.)

B24Fox wrote on 2022-12-28, 04:19:

Same question about the verification of this fix: "unlocked core voltages for undervolting"

This is the only part of the mod that actually changes a voltage, though not as extreme as it might sound: The BIOS keeps a list of the possible core voltages the onboard power controller chip can provide. Depeding on the processor, an excerpt of this list is presented to the user in the BIOS setup menu. In the stock BIOS, these are just the CPU's nominal voltage as well as a few overvolting options. The power controller chip is instructed to output the voltage chosen by the user.

The mod extends the excerpt of the list displayed in the setup menu to include all undervolting options down to 1.30 V. The way the power controller is instructed to apply the voltage is unchanged, however.

B24Fox wrote on 2022-12-28, 04:19:

So basically my question is that, with the modifications that could affect voltages; were the voltages checked afterwords to confirm the actual values presented in the BIOS?

The first two changes are more cosmetical in nature. The last change has been independently checked by various people. User BitsUndBolts has made a video using the mod to undervolt a Pentium II, in which he measures the core voltage externally:

BitsUndBolts wrote on 2022-11-21, 11:13:

I recently made a video (Undervolted Pentium II) undervolting a Pentium II 400. The minimum voltage I can select is 1.55V - and the CPU is still stable.

B24Fox wrote on 2022-12-28, 04:19:

Great work @DenizOezmen btw!
And thank you!

Appreciated, thanks!

Thank you very much for your very detailed answer!
I'm certainly gonna have to revisit this thread when I start rebuilding/upgrading my ASUS P3B-F "all-in-1 / multi-purpose" machine 😀

BitsUndBolts wrote on 2023-01-07, 15:14:

I have used the latest BIOS mod with unlocked voltages on an ASUS P3B-F and published the follow-up video Undervolted Pentium II - Tying up loose ends.
In this video, I could undervolt a PII and PIII to 1.45/1.50 Volts and I did not encounter any issues.

By the way, since I've watched your boot block/hot flashing video 😀 -- here's a rough sketch of the P3B-F's ROM layout for reference. Maybe it will make analyzing the effects of flashing "with" or "without" boot block easier:

1addresses    size  content
200000-1ffff  128K  companion data/modules (microcodes, EPA logo, ... -- everything you can add/remove using CBROM)
320000-33fff   80K  main module
434000-37fff   16K  ASUS-specific extension to the main module, gets loaded during POST
5-----------------  ^^^ compressed content above ^^^  // vvv uncompressed content below vvv
638000-38fff    4K  configuration area (DMI)
739000-39fff    4K  configuration area (ESCD)
83a000-3afff    4K  decompression code
93b000-3ffff   20K  boot block

The boot process always starts in the boot block. At some point, the code will try to validate the checksums of the decompression routines and the compressed main module. If both check out, the main module is decompressed and control is handed over, else the flow of execution stays within the boot block (roughly speaking -- there's a lot of copying stuff between various segments involved).

There's something that might be a bug in ASUS's implementation: Their own extension at address 0x34000 gets uncompressed before the main module, but it seems like the checksum of the decompression routines is not validated beforehand. So, if part of the image containing the decompression code is damaged, there's a good chance the system will simply hang instead of continuing in recovery mode.

I assume that the flash tool more or less ignores what the flash chip manufacturer has designated as the protected boot block area and handles the layout itself, since the most important layout information is stored within the image.

Very interesting details - Thanks for sharing! I am no expert in BIOS routines - yet 😀
But I can imagine that you're right - the flashing tool may just handle the layout itself - ignoring the dedicated memory blocks intended by the chip manufacturer.
Once I get my hands on a good programmer, I may redo those tests and analyze what remains on the chip after power-cuts at different stages in the flashing process.
That may be a very blunt way of analyzing what is going on, but may be easy to understand.

DenizOezmen wrote on 2023-01-07, 00:34:

Hi, […]
Show full quote

Hi,

RaVeNsClaw wrote on 2023-01-06, 19:38:

The problem:
The VCORE is automatically set to 1.98V and cannot be changed.

Wow, that is bad and shouldn't happen. Thanks for notifying.

I couldn't reproduce the problem exactly the same way, but there seems to be something wrong with the dynamic patch that determines the upper VCore limit. I've changed the code to be less intrusive. Could you try this? (Obviously, the Tualatin CPU shouldn't be running in this board with the old mod build ...)

In the meantime, I'll be pulling the other builds until we're sure the new build works.

I have now tested the BIOS, but the behaviour is the same as before.

However, I'm now shure, that it's my own fault.
I made the modification to the CPU 14 years ago for an i815 chipset. The bridged PINs are different from the pictures found on the net for the BX chipset.

I will put the Tualatin back into the i815 board and run the CUBX with a Coppermine.

I'm very sorry for the trouble! I haven't worked with S370 hardware for ages.

RaVeNsClaw wrote on 2023-01-12, 19:53:

I made the modification to the CPU 14 years ago for an i815 chipset. The bridged PINs are different from the pictures found on the net for the BX chipset.

I will put the Tualatin back into the i815 board and run the CUBX with a Coppermine.

I'm very sorry for the trouble! I haven't worked with S370 hardware for ages.

No worries; better safe than sorry.

Thanks for the explanation; it makes sense now. If the modification of the VID pins is not compatible, the board might read an invalid VID. In that case, the behavior of the BIOS can be traced in the code. Even the graphical corruption follows as observed. (This should have happened with the stock BIOS as well.)

DenizOezmen wrote on 2023-01-07, 09:20:

maxtherabbit wrote on 2023-01-07, 02:00:

I can't seem to find the P3B-F BIOS anymore... even the version prior to the VCore change...

I was going to try flashing mine tomorrow 🤣

Sorry about that!
Until the bug has been confirmed resolved, here's the last released build before the possibly problematic change.

I've been using this BIOS for a few weeks now. It works great with one problem - the ACPI implementation seems totally broken. The only way I can get Windows XP or 2000 to install is to use F5 and choose "Standard PC" during the setup. Booting from Hiren's mini XP works, but if you try to shut down the system it just hangs, no poweroff. Even the DOS SHUTDOWN utility (which uses APM I believe) just freezes.

I don't know if this is as a result of the mods, of if these problems were present in the original P3B-F BIOS. The main issue is there is no setting in the CMOS setup to disable ACPI. Any thoughts?

maxtherabbit wrote on 2023-01-25, 20:35:

I've been using this BIOS for a few weeks now. It works great with one problem - the ACPI implementation seems totally broken. The only way I can get Windows XP or 2000 to install is to use F5 and choose "Standard PC" during the setup. Booting from Hiren's mini XP works, but if you try to shut down the system it just hangs, no poweroff. Even the DOS SHUTDOWN utility (which uses APM I believe) just freezes.

I don't know if this is as a result of the mods, of if these problems were present in the original P3B-F BIOS. The main issue is there is no setting in the CMOS setup to disable ACPI. Any thoughts?

The mod shouldn't affect ACPI. From what I've read of others operating Pentium Pros on (ASUS) BX/LX boards, shutdown problems are common. It seems like either there's a hardware compatibility issue or a problem with the SMI handlers that react to APM command writes to the PIIX southbridge. (Boards with Via chipsets are less problematic.)

I could try and disable as many handlers as possible. Maybe that gives some insight -- no promises, though.

By the way, which shutdown utility exactly?

DenizOezmen wrote on 2023-01-27, 22:37:

The mod shouldn't affect ACPI. From what I've read of others operating Pentium Pros on (ASUS) BX/LX boards, shutdown problems ar […]
Show full quote

maxtherabbit wrote on 2023-01-25, 20:35:

I've been using this BIOS for a few weeks now. It works great with one problem - the ACPI implementation seems totally broken. The only way I can get Windows XP or 2000 to install is to use F5 and choose "Standard PC" during the setup. Booting from Hiren's mini XP works, but if you try to shut down the system it just hangs, no poweroff. Even the DOS SHUTDOWN utility (which uses APM I believe) just freezes.

I don't know if this is as a result of the mods, of if these problems were present in the original P3B-F BIOS. The main issue is there is no setting in the CMOS setup to disable ACPI. Any thoughts?

The mod shouldn't affect ACPI. From what I've read of others operating Pentium Pros on (ASUS) BX/LX boards, shutdown problems are common. It seems like either there's a hardware compatibility issue or a problem with the SMI handlers that react to APM command writes to the PIIX southbridge. (Boards with Via chipsets are less problematic.)

I could try and disable as many handlers as possible. Maybe that gives some insight -- no promises, though.

By the way, which shutdown utility exactly?

Interesting, do you know if it would be possible to enable a hidden setting in the BIOS to disable ACPI outright perhaps?

The shutdown utility is whichever one is included in the CDU release package of MS-DOS 7.1 (on REMOVED)

maxtherabbit wrote on 2023-01-27, 23:48:

Interesting, do you know if it would be possible to enable a hidden setting in the BIOS to disable ACPI outright perhaps?

There are no interesting hidden menu items as far as I can tell. Maybe it's possible to neuter ACPI by removing the ACPI tables module. The test build below does that.

maxtherabbit wrote on 2023-01-27, 23:48:

The shutdown utility is whichever one is included in the CDU release package of MS-DOS 7.1 (on REMOVED)

Thanks! Yes, this tool uses APM functions through int 15h.

I don't think ACPI per se is the problem here. It seems like all methods (setting power states through ACPI or through APM int 15h) boil down to the same mechanism: A write to the APMC register of the southbridge is performed, which causes an SMI. The SMI handler reads the command from the register and chooses an appropriate handling routine. The routine for performing a "soft off" (assuming I found the right one) is pretty long-winded and has multiple interactions with the power configuration and probably the SMBus(?) I/O space of the southbridge.

Could you try the attached test version of the shutdown tool? It should print some additional messages. I suspect it to hang after printing "Setting power state" ...

DenizOezmen wrote on 2023-01-28, 13:29:

There are no interesting hidden menu items as far as I can tell. Maybe it's possible to neuter ACPI by removing the ACPI tables […]
Show full quote

maxtherabbit wrote on 2023-01-27, 23:48:

Interesting, do you know if it would be possible to enable a hidden setting in the BIOS to disable ACPI outright perhaps?

There are no interesting hidden menu items as far as I can tell. Maybe it's possible to neuter ACPI by removing the ACPI tables module. The test build below does that.

maxtherabbit wrote on 2023-01-27, 23:48:

The shutdown utility is whichever one is included in the REMOVED release package of MS-DOS 7.1 (on REMOVED )

Thanks! Yes, this tool uses APM functions through int 15h.

I don't think ACPI per se is the problem here. It seems like all methods (setting power states through ACPI or through APM int 15h) boil down to the same mechanism: A write to the APMC register of the southbridge is performed, which causes an SMI. The SMI handler reads the command from the register and chooses an appropriate handling routine. The routine for performing a "soft off" (assuming I found the right one) is pretty long-winded and has multiple interactions with the power configuration and probably the SMBus(?) I/O space of the southbridge.

Could you try the attached test version of the shutdown tool? It should print some additional messages. I suspect it to hang after printing "Setting power state" ...

I suspect you are correct about the shutdown problem, I will try both of these test versions and get back.

Truth is, the shutdown thing isn't really my concern. My concern with ACPI is that neither WinXP nor Win2k will even install without forcing a non-ACPI HAL. They just hang in the installers. Most live linux CDs won't boot either, notably including Acronis true image 2011 which usually works on everything

maxtherabbit wrote on 2023-01-28, 14:55:

Truth is, the shutdown thing isn't really my concern. My concern with ACPI is that neither WinXP nor Win2k will even install without forcing a non-ACPI HAL. They just hang in the installers. Most live linux CDs won't boot either, notably including Acronis true image 2011 which usually works on everything

It's likely all somehow connected. Regarding Windows, it might also be possible to force APM installations by setting back the BIOS build date. No idea if Linux distributions have a similar mechanism.

DenizOezmen wrote on 2023-01-28, 13:29:

There are no interesting hidden menu items as far as I can tell. Maybe it's possible to neuter ACPI by removing the ACPI tables […]
Show full quote

maxtherabbit wrote on 2023-01-27, 23:48:

Interesting, do you know if it would be possible to enable a hidden setting in the BIOS to disable ACPI outright perhaps?

There are no interesting hidden menu items as far as I can tell. Maybe it's possible to neuter ACPI by removing the ACPI tables module. The test build below does that.

maxtherabbit wrote on 2023-01-27, 23:48:

The shutdown utility is whichever one is included in the REMOVED release package of MS-DOS 7.1 (on REMOVED )

Thanks! Yes, this tool uses APM functions through int 15h.

I don't think ACPI per se is the problem here. It seems like all methods (setting power states through ACPI or through APM int 15h) boil down to the same mechanism: A write to the APMC register of the southbridge is performed, which causes an SMI. The SMI handler reads the command from the register and chooses an appropriate handling routine. The routine for performing a "soft off" (assuming I found the right one) is pretty long-winded and has multiple interactions with the power configuration and probably the SMBus(?) I/O space of the southbridge.

Could you try the attached test version of the shutdown tool? It should print some additional messages. I suspect it to hang after printing "Setting power state" ...

Your suspicion confirmed

BootROMError8046 wrote on 2021-06-19, 21:11:

Well, it doesn't work unfortunately. But I found an old Russian article about running a ppro in a 440bx board, so I'll have a read. Really appreciate your help bud/maam!!

Very glad to hear that this article did help! I was co-author this article (Emil from Baku), in BIOS mod part.

DenizOezmen wrote on 2023-01-27, 22:37:

The mod shouldn't affect ACPI. From what I've read of others operating Pentium Pros on (ASUS) BX/LX boards, shutdown problems are common. It seems like either there's a hardware compatibility issue or a problem with the SMI handlers that react to APM command writes to the PIIX southbridge. (Boards with Via chipsets are less problematic.)

Yes, I know about this problem - hanging after software call SMM handler (write to port 0xB2).
Unfortunately, I did not end our investigation, after ~1 month after article publication,
I was ill seriously and forgot about it.

Currently I have no PPro->Slot1 converter for HW experiments, but I remember about this problem.
Probably, it is software problem, as the first earlier BIOS for ASUS P2L97/P2L97-S (0102) do write
to port 0xB2 without hanging with PPRO.

There is no Pentium Pro to Slot 1 adapter left anywhere on sale at, eBay, Aliexpress, Newegg, Amazon etc. The Pentium Pro adapter can only be used with 66 MHz bus. Not all mainboards can support this fsb, like i815 and i820 chipset. The performance of Pentium Pro is up to 233 MHz with of the die 256 to 512kb cache, but in the same package. This speed can easily be passed even with Celeron 300A on some benchmarks. So there is no logical reason to waste your money playing on Pentium Pro. New motherboard but, older processor. Something like a couple with between 30 years of age difference!

Slot 1 architecture is a real good design. The SECC2 processors even much better with coppermine core being Pentium 3. With a 600E processor as an example, this processor has 100MHz fsb. It can easily be downgradeable to 66 MHz, can work at 400 MHz and can be undervolted. It is also possible to rise the fsb to 133 MHz and it is rock stable at 800 MHz, still no need to increase Voltage. This processor is much more better buy, than a Pentium Pro for an enthusiast. There are also Tualatins, they are really good playable ones too. Who needs a slower processor, on a much modern motherboard. Unless necessary? Really....

karakarga wrote on 2023-02-04, 22:51:

There is no Pentium Pro to Slot 1 adapter left anywhere on sale at, eBay, Aliexpress, Newegg, Amazon etc. The Pentium Pro adapter can only be used with 66 MHz bus. Not all mainboards can support this fsb, like i815 and i820 chipset. The performance of Pentium Pro is up to 233 MHz with of the die 256 to 512kb cache, but in the same package. This speed can easily be passed even with Celeron 300A on some benchmarks. So there is no logical reason to waste your money playing on Pentium Pro. New motherboard but, older processor. Something like a couple with between 30 years of age difference!

Slot 1 architecture is a real good design. The SECC2 processors even much better with coppermine core being Pentium 3. With a 600E processor as an example, this processor has 100MHz fsb. It can easily be downgradeable to 66 MHz, can work at 400 MHz and can be undervolted. It is also possible to rise the fsb to 133 MHz and it is rock stable at 800 MHz, still no need to increase Voltage. This processor is much more better buy, than a Pentium Pro for an enthusiast. There are also Tualatins, they are really good playable ones too. Who needs a slower processor, on a much modern motherboard. Unless necessary? Really....

Yes, I understand your opinion. But Pro very interesting for me as low-level programmer,
because it has a lot thin differences from Pentium 2/3. BTW, I run PPro on P3B-F motherboard
with FSB 100 and multiplier 2. It worked absolutely stable! It would be interesting, to try out
PPro on i820 chipset with FSB100! IIRC, i815 supported FSB66, just RAM speed will be 100MHz.

For regular work I usually use Pentium2/3. And yes, currently I have no any Slot1->Socket8 converter,
but I have the native PPro motherboard P6AN (i440FX chipset) for experiments.

maxtherabbit wrote on 2023-01-30, 20:59:

Your suspicion confirmed

Thanks for checking!

i386 wrote on 2023-02-03, 13:51:

Very glad to hear that this article did help! I was co-author this article (Emil from Baku), in BIOS mod part.

Thanks a lot for your work and the documentation! The MSR stuff was straightforward enough to find out, but having no Pentium Pro hardware at hand, I probably would not have located the APMC write problem.

i386 wrote on 2023-02-03, 13:51:

Currently I have no PPro->Slot1 converter for HW experiments, but I remember about this problem.
Probably, it is software problem, as the first earlier BIOS for ASUS P2L97/P2L97-S (0102) do write
to port 0xB2 without hanging with PPRO.

Good to know. Do you happen to remember the specific build where support broke? Maybe comparing SMI handlers between two versions can shed light on the problem.

DenizOezmen wrote on 2023-02-05, 13:49:

Thanks a lot for your work and the documentation! The MSR stuff was straightforward enough to find out, but having no Pentium Pro hardware at hand, I probably would not have located the APMC write problem.

Thank you also! You are doing a very helpful job!!

DenizOezmen wrote on 2023-02-05, 13:49:

Good to know. Do you happen to remember the specific build where support broke? Maybe comparing SMI handlers between two versions can shed light on the problem.

Yes, I remember! IIRC, ASUS BIOS for P2L97 lx2i0102.zip worked with PPRO, no shutdown problem.
https://www.elhvb.com/mobokive/Archive/Asus/s … 2l97/index.html
More modern BIOS-es for this board - no PPRo support. But I did not modified intermediate
P2L97 BIOS-es for PPRo support and I do not know about APWC problem in them. Anyhow,
latest BETA BIOS for P2L97 (from official suite) definitely has the APWC problem.

Absolutely same situation with P2L97-S, earlier BIOS lx2s0102.zip worked with PPRo
https://www.elhvb.com/mobokive/Archive/Asus/s … 97-s/index.html
Latest BETA - no.

P2L97-S I tested myself with PPRO, P2L97 tested my friend (Max1024), that wrote
article (he tested the P2L97-S also).

PS. Currently I'm repairing the ASUS P2L97-DS after severe damage.

karakarga wrote on 2023-02-04, 22:51:

There is no Pentium Pro to Slot 1 adapter left anywhere on sale at, eBay, Aliexpress, Newegg, Amazon etc. The Pentium Pro adapter can only be used with 66 MHz bus. Not all mainboards can support this fsb, like i815 and i820 chipset. The performance of Pentium Pro is up to 233 MHz with of the die 256 to 512kb cache, but in the same package. This speed can easily be passed even with Celeron 300A on some benchmarks. So there is no logical reason to waste your money playing on Pentium Pro. New motherboard but, older processor. Something like a couple with between 30 years of age difference!

Slot 1 architecture is a real good design. The SECC2 processors even much better with coppermine core being Pentium 3. With a 600E processor as an example, this processor has 100MHz fsb. It can easily be downgradeable to 66 MHz, can work at 400 MHz and can be undervolted. It is also possible to rise the fsb to 133 MHz and it is rock stable at 800 MHz, still no need to increase Voltage. This processor is much more better buy, than a Pentium Pro for an enthusiast. There are also Tualatins, they are really good playable ones too. Who needs a slower processor, on a much modern motherboard. Unless necessary? Really....

1) u just posted cringe ur going to lose subscriber
2) my pentium pro is running at 120MHz FSB on my P3B-F so cope

i386 wrote on 2023-02-05, 14:10:

Yes, I remember! IIRC, ASUS BIOS for P2L97 lx2i0102.zip worked with PPRO, no shutdown problem. https://www.elhvb.com/mobokive/A […]
Show full quote

Yes, I remember! IIRC, ASUS BIOS for P2L97 lx2i0102.zip worked with PPRO, no shutdown problem.
https://www.elhvb.com/mobokive/Archive/Asus/s … 2l97/index.html
More modern BIOS-es for this board - no PPRo support. But I did not modified intermediate
P2L97 BIOS-es for PPRo support and I do not know about APWC problem in them. Anyhow,
latest BETA BIOS for P2L97 (from official suite) definitely has the APWC problem.

Thank you, that is interesting! I've taken a quick look. On a first glance at the 0102 BIOS, I can't find any positions where the code actually reads anything from port 0xB2. Maybe the handlers are still missing there?
In any case, the latest P2L97 BIOS has fewer handlers than the P3B-F. I wonder whether the generation of SCIs (which are ACPI-specific as far as I understand) might be a problem.

I've attached a test build that (aside from removing the ACPI table) disables two handlers that might be responsible for switching between SCI and SMI generation.

maxtherabbit wrote on 2023-01-28, 14:55:

I suspect you are correct about the shutdown problem, I will try both of these test versions and get back.

@maxtherabbit: Could you test this one if you find the time?

i386 wrote on 2023-02-05, 14:10:

PS. Currently I'm repairing the ASUS P2L97-DS after severe damage.

Oh, a dual board. What happened to it?